A common problem in the manufacture of hybrid circuits is that of providing interconnections between high frequency and/or wide band, controlled impedance circuits, such as microstrip circuits, and discrete electronic devices, such as diodes and transistors. A common approach is to place the electronic device in a slot in the substrate on which the controlled impedance circuit is carried. Standard wire bond techniques are then used to connect the signal carrying conductors on the surface of the substrate adjacent to the slot to the terminals of the electronic device. However, since the electrical characteristics of the wires bridging between the signal conductors and the device terminals are substantially different from those of the controlled impedance transmission line and because of the unpredictable nature of the electrical characteristics of the junctions, this interconnection technique substantially degrades the electrical performance of the circuit. This is particularly crucial in applications requiring very high frequency, wide band and/or low signal to noise ratio performance.